There are a couple of applications that work with Firfox, one works with MSIE as well (I do not know about the other)
X-marks saves your favorites and syncs them (Via an external server) with all yor assorted copies of Firefox
Last Pass saves both favorites and passwords. but does it differently (They are saved in your "Last pass vault" not in your bookmarks/favorites file).
So any web site I have LOGGED INTO (Last pass only works if there is a password). I can log into from this laptop. The desktop.. The androids, Someone else's computer, A library computer.. ANY web connected computer.